According to the related art, as a coating material at the time of manufacturing synthetic leather, polyurethane or polyvinylchloride (PVC) have been mainly used. In a method for manufacturing synthetic leather using polyurethane, synthetic leather is manufactured using a polyurethane impregnation material containing 20 to 80 parts by weight of a solid component formed by polymerizing polyol, a chain extender, isocyanate, and the like in a presence of an organic solvent such as dimethylformamide, methylethylketone, or the like, and having a viscosity of 50,000 to 150,000 cps/25° C. and a coating material. This method is generally divided into a dry method and a wet method.
In the dry method, polyurethane is used as a coating layer and an adhesive layer, and a film is formed by coating a coating solution in which polyurethane, dimethylformamide, methylethylketone, and a pigment are mixed with each other at a suitable ratio on a release paper at least one time and passing the release paper through a drier to volatilize the solvent. In addition, after coating the film again with a coating solution in which a polyurethane adhesive, a curing agent, a curing accelerator, dimethylformamide, and methylethylketone are mixed with each other at a suitable ratio, a textile is adhered thereto using an adhesive and sufficiently cured, and then, the release paper is peeled off, thereby manufacturing a polyurethane synthetic leather.
However, in the case of the synthetic leather manufactured as described above, a working environment problem due to usage of the organic solvent and an environmental problem due to the organic solvent remaining in a final synthetic leather product have been generated.
Therefore, recently, a method for manufacturing synthetic leather using a water dispersion polyurethane that does not contain an organic solvent has been studied and developed, but there is difficulty in a manufacturing process such as processability, or the like, economical efficiency for commercialization may be insufficient, and this method does not satisfy various and improved physical properties as the synthetic leather, such that it is difficult to commercialize this method.
Therefore, the present applicant studied a method for manufacturing synthetic leather using liquid silicone rubber (LSR) in order to solve the existing environmental problems and satisfy the improved physical properties required as synthetic leather (Korean Patent Laid-Open Publication No. 2003-0095872), but in the case of the synthetic leather manufactured by this method, there was disadvantages to be described below in using this synthetic leather in various uses such as an interior material, miscellaneous goods, or the like.
First, in the case of synthetic leather to be used as an interior material of an aircraft or ship, very strict physical properties are required (for example of mainly required physical properties, there are vertical flame retardancy, smoke density, a heat release amount, and the like), but the existing method did not satisfy the above-mentioned physical properties.
Second, in the case of synthetic leather for furniture, an interior material of a vehicle, or various miscellaneous goods, a suitable adhesion strength in order to allow a coating layer not to be peeled off at the time of usage and various properties such as flame retardancy, heat resistance, contamination resistance, solvent resistance, hydrolysis resistance, and the like, are required, but the existing method did not satisfy the above-mentioned physical properties.